Improvement in door-pulleys



UNITED STATES PATENT CEEIoE.

IVILLIAM A. HOLVELL, OF QUEBEC, CANADA.

IMPROVEMENT IN DOOR-PULLEVS.

Specification forming part of Letters Patent No. 146,675, dated January 20, 1874; application filed August 4, 1873.

` view of the same.

This invention has relation to means for automatically closing doors; and it consists 1n the construction and novel arrangement of the parts constituting` a tripartite door-pulley having the worm or screw-groove formed at its ends on cylinders of varying lengths and small diameters, and between said end cylinders on an intermediate enlargement or cylinder of greater diameter, said groove being continuous from one end to the other of the pulley, and being designed for the passage ot' the weightcord, which is attached by one end to the door, as hereinafter more fully described. rIhe object of this invention is to provide means whereby a door, in the first place, may be automatically closed, and, in the second place, held closed with considerable force. Finally, it is designed to enable the door to be opened widely without much exertion and to be readily held open.

In the accompanying drawings, the letter A designates the pulley, and B the bracket in ,which it-iis' hung, and by means of which it is attached to the wall of a recess in the doorj amb or other suitable place. The intermediate or enlarged portion of the pulley lettered a on the drawings is usually nearer one end than 0f these ends b designates the c designates the the other. shorter, and b' the longer.

cord attached by one end to the door, wound several times about the pulley, and provided at its other end with a pendent weight, w. This cord maybe secured to the enlarged portion of the pulley at about the point marked d on the drawings'. e designates the cordgroove, which is helical and continuous from one end of the pulley to the other, passing from the more contracted ends to and from the enlargement a by means of spiral or scroll-like steps, a.

The cord is designed to be attached to the pulley in such a manner that when the dooi` is closed that branch of the cord which is attached to the door will be wound upon the small cylinder b, passing thence .by the step a to the enlargement a, from which the weight hangs. In this position the difference in leverage between the enlargement c and the end cylinder b causes the door to be held closed with considerable force.

When the door is opened, the doorbranch of the cord will be run upon the enlargement a, and the weight-branch thereof will be run out upon the long end cylinder b., from which the weight will hang. In this position while the weight has sufficient force to automatically close the door, if not held open, the diiierence in leverage between the enlargement a and cylinder b lessens this force, so that the door may be readily moved.

I am aware that differential pulleys resembling mine have been used in spinningmaehines and hay-presses. I do not, therefore, claim such a pulley broadly; but

What I claim as my invention, and desire to secure by Letters Patent, is-

The triple doorpulley hung in the bracket B in the door-frame, and having the end cylinders b b', the intermediate enlargement a, the spiral steps a', and the helical cord-groove c, continuous fromend to end of the pulley, in connection with the cord c attached to the door and weight w, as and for the purpose specified.

Quebec, 31st July, 1873.

1V. ANTROBUS HOLIVELL.

IVitnesses:

W. DARLING CAMPBELL,

of Quebec, Notary Public. JAs. ALLPU, of Quebec, Notary Public.V 

